Flush the cooling system of Jeep Grand Cherokee 2001

There are three parts for cooling system of a typical vehicle: radiator, reservoir and engine block. There is a plastic drain plug underneath the radiator which can drain the coolant in the radiator and reservoir.

However, it is not an easy job to drain the coolant in the engine block of Jeep grand Cherokee 2001, since the drain plug located under the intake manifold is a female pipe plug. We need a 5/16" male pipe plug socket to take  it  down. Despite the possibility that the plug would be rusted and get stuck in the engine block, the 5/16" pipe plug socket is very rare in the Canadian market. I searched around the city of London in Canadian Tire, Part Source, Rona, NAPA, Home Depot and Federated Tools, without any luck.

The original coolant in my Jeep is the conventional ethylene glycol based green coolant. I cannot change it to the more advanced orange long life HOAT coolant because mixing green coolant with the orange type would produce some sediments in the cooling system which are highly harmful to the components of the cooling. system.

An informative article by James B. Wills, Jr.  reads

An alternative to tradition green antifreeze is a product currently used by many engine manufacturers. "Orange" antifreeze is a long life or extended life type of antifreeze used to increase the useful life of engine coolant. It is ethylene glycol base as is the green antifreeze. The difference between the two colors is that orange antifreeze contains a different type of corrosion inhibitor that has a much longer service life than silicates, phosphates and borates. Orange antifreeze contains organic acids that protect engine parts from corrosion. Silicate (green) type antifreeze does not mix with orange type antifreeze. Never mix the two colors in a cooling system. The organic acids in orange types will cause precipitation of silicates in the green type and corrosion protection is greatly reduced.

Now that it was difficult to drain the green coolant  in the engine block, I had to stick with the green coolant and just replace the old coolant in the radiator several times. The following is what I did today:

1. Bought two jugs of concentrated regular coolant from Jeep dealership. 2X 3.78 Liter, 17.7 CAD per jug;

2. Bought two jugs of distilled and ozonated water. 2 X 4 Liter. 1.67 CAD per jug. Open the lids and dispose them in sunshine for two hours letting the ozone out;

3. Use a 2 feet gardening hose as an extension to the original drainage hose at  the drain plug and put one end of the extension hose into a bucket with measure scale;

4. Open the drain plug located at the left corner of the radiator facing the rear of the vehicle (NOTE: The service manual said it was at the right corner of the radiator!); That is, it is to the passenger' side. Then twist the valve counter clock-wisely 270 degree.

5.  The total amount of the old coolant drained from the radiator and the reservoir is 7.5 liters, which is 60% of the coolant in the cooling system (12.3 liters).

6. Put a half jug of the concentrated coolant into the radiator and then a half jug of the distilled water;

7. Mix the remaining half jugs of water and concentrated coolant together. Pour the mixed coolant into the radiator and the reservoir jug.

8. Let the car run for at least 10 minutes and bring the system into working temperature. Repeat 1--7 after the system cools down.

The following are simple arithmetics: After the first round (step 1 -- 7),   60% old coolant was replaced; After the second round, 84% was replaced;